Bloomston M et al. (2007) MicroRNA expression patterns to differentiate pancreatic adenocarcinoma from normal pancreas and chronic pancreatitis. JAMA 297: 1901–1908

Researchers in the US have identified a global microRNA (miRNA) expression pattern that can differentiate pancreatic cancer from either normal pancreas or chronic pancreatitis with 95% accuracy.

miRNAs are small noncoding RNA molecules that bind to messenger RNA causing its inhibition or degradation. By inhibiting the expression of tumor-suppressor genes or promoting proto-oncogene expression, aberrant miRNA expression can promote carcinogenesis in human cancers.

Bloomston and colleagues collected diseased pancreatic tissue samples from patients with ductal adenocarcinoma of the pancreas (n = 65) and chronic pancreatitis (n = 42). Tissue samples were also collected from adjacent benign areas of the pancreas in all pancreatic cancer patients. RNA was extracted from these samples, and hybridized to miRNA microarrays. The team found 25 miRNAs for which expression was either increased or decreased in pancreatic cancer, and could correctly distinguish benign from cancerous tissue in 90% of samples. They also found 23 miRNAs with an expression profile that could distinguish cancer from chronic pancreatitis with 93% accuracy. Long-term survivors of pancreatic cancer who had positive lymph nodes could be distinguished from short-term survivors who died within 24 months by the differential expression patterns of six miRNAs. High expression of one miRNA, miR-196a-2, was predictive of poor survival (P = 0.009).

The authors conclude that their preliminary findings might, with further validation, enable clinicians to differentiate between benign and malignant tissue and between patients with better and worse prognoses, which would help guide management decisions.